Staff: Mentor

I sincerely doubt it will be brighter than the moon. What is it's albedo, size, and closest approach to the Earth?

A comet's brightness doesn't have much to do with albedo and size prior to entering the inner solar system. It's a comet -- what we see is mostly gas and dust, ejected when it nears the sun.

But:

Philosophiae said:

During the final stage near the sun the Ison comet will be visible during the day and brighter than the moon.

May. It may be brighter than the moon. It is still very iffy at this point. We won't even know if it will survive its brush with the sun until it happens and it will change very rapidly. So every day will be like opening a Christmas present for astronomers. I just hope it isn't socks.

A comet's brightness doesn't have much to do with albedo and size prior to entering the inner solar system. It's a comet -- what we see is mostly gas and dust, ejected when it nears the sun.

But:
May. It may be brighter than the moon. It is still very iffy at this point. We won't even know if it will survive its brush with the sun until it happens and it will change very rapidly. So every day will be like opening a Christmas present for astronomers. I just hope it isn't socks.

I tend to agree with your slight scepticism. Predicting appearance even with good data is nothing but speculation. I remember all the hullabaloo about the return of Halley’s. What a let down!

Staff: Mentor

In November 2013 the comet Ison will be visible , spectacular, brighter than the moon:

Something like 30-60km across. Apparently there is an even chance it will collide with Mars. If so, at 60km/sec it should leave a crater around 300km across. The fireworks will be visible to the naked eye from Earth, for those favourably positioned. Were it to collide with Earth, the result would be similar to the event that wiped out the dinosaurs.

Something like 30-60km across. Apparently there is an even chance it will collide with Mars. If so, at 60km/sec it should leave a crater around 300km across. The fireworks will be visible to the naked eye from Earth, for those favourably positioned. Were it to collide with Earth, the result would be similar to the event that wiped out the dinosaurs.

That's a few details I remember from a recent astronomy broadcast.

no ... wrong comet
This one is the possible Mars contender .....C/2013 A1 (Siding Spring) is a new discovery by Robert McNaught on January 3. This comet will pass very close to Mars on the 19th of October 2014. There is a small possibility that it may impact the planet! It is not currently observable visually

no ... wrong comet
This one is the possible Mars contender .....C/2013 A1 (Siding Spring) is a new discovery by Robert McNaught on January 3. This comet will pass very close to Mars on the 19th of October 2014. There is a small possibility that it may impact the planet! It is not currently observable visually

Dave

If it did hit, can you imagine the pictures that some of the rovers might get right before they're vaporized?

Staff: Mentor

But, let me just mind you that the tail is exaggerated... alot... but still worth gazing atevery second.

It isn't necessarily exaggerated. In fact, it may be under-playing it. The tail could be long enough to stretch nearly from horizon to zenith, but what Starry Night doesn't pick up is that the comet is moving so fast that the tail drags across the sky like a fan. See The Great Comet of 2007:

I well remember the impact marks on Jupiter of Shoemaker-Levy9 in 1994
WHAT an amazing birthday pressie!!

These fragments collided with Jupiter's southern hemisphere between July 16 and July 22, 1994, at a speed of approximately 60 km/s (37 mi/s) or 216,000 km/h (134,000 mph). The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months.

I didnt have the ability to photo the impact sites back then, but seeing those black marks on Jupiter through my own scope was awesome

Staff: Mentor

If it did hit, can you imagine the pictures that some of the rovers might get right before they're vaporized?

Even if there isn't a direct hit, the astronomer said that it could well spell the end of our spotlight on Mars. Our Mars satellite/s that relay data from the Rovers will not fare well. The comet by the time it passes Mars is likely to have broken up into something akin to an expanding swarm of rocks, gravel and smaller particles, and some are sure to head towards Mars. The particles and the cloud they kick up may destroy the satellites, and with that our vital link to the Rovers.

Staff: Mentor

no ... wrong comet
This one is the possible Mars contender .....C/2013 A1 (Siding Spring) is a new discovery by Robert McNaught on January 3. This comet will pass very close to Mars on the 19th of October 2014. There is a small possibility that it may impact the planet! It is not currently observable visually